Various types of augmented reality systems have been developed which combine digitally generated audio and/or video with the real-time audio and video that a user perceives in a particular location or environment. For example, an augmented reality tour may use the camera and microphone of a smart phone to capture real-time audio and video while combining or overlaying interesting facts based on the location or position of the user, or based on a button-press or voice request for additional information. In one prototype of an audio augmented reality system, microphone equipped headphones are used to provide a framework for experiments including real-time audio alteration, multi-modal sensory integration, and collaborative listening experiences.